Pixel-based Spatial Light Modulators (“SLMs”) can be used to modulate an incoming optical signal. A spatial light modulator (SLM) consists of an array of optical elements (pixels) in which each pixel acts independently as an optical “valve” to adjust or modulate light intensity. An SLM does not create its own light, but rather modulates (either reflectively or transmissively) light from a lamp or other light source to create a dynamically reconfigurable digital image. Technologies that have been used as spatial light modulators include acousto-optic modulators, liquid-crystal devices, and mirror arrays such as digital micromirror devices (DMDs) and grating light valve (GLV) devices.
SLMs can be used in many contexts, such as in projection displays, printing, telecommunications, direct-write lithography and in other types of optical signal processing. For instance, in a telecommunications context, an optical signal propagating through an optical network can have multiple different channels or carrier wavelengths. SLMs are capable of equalizing, filtering, modulating, and controlling such optical signals.
Various devices in which SLMs are employed include, without limitation, dynamic gain equalizers, optical switches, display devices, attenuators, dynamic diffractive optical elements, beam steering devices, photolithographic laser mask writers and the like. The functionality of these devices are not mutually exclusive. For instance, an SLM-based device that is used as an optical attenuator may also be used to perform optical switching.
There is a need to improve the aforementioned SLM-based devices when they are used to perform attenuation.